Recombinant Human Active p38 alpha Protein, CF

• Active Kinase - Active p38 alpha (0.1 μg/μL) diluted with Kinase Dilution Buffer III as shown in Figure 2. Note: These are suggested working dilutions. Optimal dilutions should be determined by each laboratory for each application.
• Kinase Assay Buffer I - 25 mM MOPS, pH 7.2, 12.5 mM beta -glycerolphosphate, 25 mM MgCl₂, 5 mM EGTA, 2 mM EDTA. Add 0.25 mM DTT to the Kinase Assay Buffer I prior to use.
• Kinase Dilution Buffer III - Kinase Assay Buffer I diluted at a 1:4 ratio (5-fold) with 50 ng/μL BSA solution.
• 10 mM ATP Stock Solution - Prepare the ATP Stock Solution by dissolving 55 mg of ATP in 10 mL of Kinase Assay Buffer I. Store 200 μL aliquots at ≤ -20 °C.
• [³³P]-ATP Assay Cocktail - Prepare 250 μM [³³P]-ATP Assay Cocktail in a designated radioactive work area by combining 150 μL of 10 mM ATP Stock Solution, 100 μL of [³³P]-ATP (1 mCi/100 μL), and 5.75 mL of Kinase Assay Buffer I. Store in 1 mL aliquots at ≤ -20 °C.
• Substrate - P38 Sub synthetic peptide (IPTTPITTTYFFFKKK) diluted in distilled water to a final concentration of 1.0 mg/mL.

1. Thaw the [³³P]-ATP Assay Cocktail in a shielded container in a designated radioactive work area.
2. Thaw the Active p38 alpha, Kinase Assay Buffer I, Substrate, and Kinase Dilution Buffer III on ice.
3. In a pre-cooled microfuge tube, add the following reaction components bringing the initial reaction volume up to 20 μL:
   a. Diluted Active p38 alpha : 10 μL
   b. Substrate (1.0 mg/mL; on ice): 5.0 μL
   c. Distilled or deionized water: 5.0 μL
4. Set up the blank control as outlined in Step 3, excluding the addition of the substrate. Replace the substrate with an equal volume of distilled or deionized water.
5. Initiate the reaction by the addition of 5 μL [³³P]-ATP Assay Cocktail, bringing the final volume up to 25 μL. Incubate the mixture in a water bath at 30 °C for 15 minutes.
6. After the 15 minute incubation period, terminate the reaction by spotting 20 μL of the reaction mixture onto individual pre-cut strips of phosphocellulose P81 paper.
7. Air dry the pre-cut P81 strip and sequentially wash in a 1% phosphoric acid solution (add 10 mL of phosphoric acid to 990 mL of distilled or deionized water) with constant gentle stirring. It is recommended that the strips be washed a total of three times for approximately 10 minutes each.
8. Count the radioactivity on the P81 paper in the presence of scintillation fluid in a scintillation counter.
9. Determine the corrected cpm by subtracting the blank control value (see Step 4) for each sample and calculate the kinase specific activity as outlined below:
   
   
   Calculation of [³³P]-ATP Specific Activity (SA) (cpm/pmol)
   Specific Activity (SA) = cpm for 5 μL [³³P]-ATP/pmol of ATP (in 5.0 μL of a 250 μM ATP stock solution; i.e. 1250 pmol)
   
   Calculation of Kinase Specific Activity (SA) (pmol/minute/μg or nmol/minute/mg)
   Corrected cpm from reaction / [(SA of ³³P-ATP in cpm/pmol) x (Reaction time in minutes) x (Enzyme amount in μg or mg)] x [(Reaction volume) / (Spot Volume)]

Scientific Data

SDS-PAGE View Larger

The approximate molecular weight is 67 kDa and the purity is > 85%.